Abstract: A gas sensor assembly detects the presence of a constituent in a first gas stream. The assembly comprises: (a) a flexible circuit having a pair of oppositely-facing surfaces, (b) a sensor mounted on one surface of the flex circuit, the sensor electrically connected to conductors in the flex circuit, and (c) a channel for directing a second gas stream across the flex circuit surface facing away from the sensor, the channel formed at least in part by the flex circuit surface facing away from the sensor. The first and second gas streams can be derived from a common gas stream. In operation, thermal conductivity between the sensor and neighboring heat-conducting structures components is reduced, thereby reducing sensor electric power consumption.

Abstract: A gas sensor for sensing a gas stream constituent includes, mounted a substrate, a first gas-sensing element capable of sensing the constituent in a first concentration range, a reference element insensitive to the constituent and having electrical properties congruent with the first gas-sensing element, a heating element substantially circumscribing the first gas-sensing element and the reference element, a temperature-sensing element circumscribing the first gas-sensing element and the reference element, and a second gas-sensing element capable of sensing the constituent in a second concentration range. The first gas-sensing element and the reference element are preferably metal-gated metal-oxide semiconductor (MOS) solid-state devices. The gas sensor is particularly configured to sense hydrogen concentration in a gas stream.

Abstract: A gas sensor assembly detects a constituent in a gaseous stream. The assembly comprises: (a) a mounting surface, (b) a sensor mounted on the mounting surface and sensor capable of generating a detectable signal in the presence of the constituent, and (c) an enclosing structure. The enclosing structure comprises: (i) a walled component having a pair of vertically spaced ends and mounted at one end on the mounting surface so as to circumscribe the sensor, and (ii) a gas-permeable membrane attached at the other end of the walled component, thereby defining an interior volume within said enclosing structure. Flowing the gaseous stream across the membrane infuses a portion of the gaseous stream into said interior volume containing the sensor.